The present disclosure relates to an evaporated fuel processing device in which a flow control valve is used as a valve to be installed in a pathway connecting a fuel tank and a canister, and in which the flow control valve is held in a valve-closed condition when a stroke amount corresponding to an axial travel distance of a valve movable element to a valve seat is equal to or less than a predetermined amount from an initial condition, so as to be capable of holding the fuel tank in a hermetically closed condition.
An evaporated fuel processing device using a flow control valve described above as a valve to be installed in a pathway connecting a fuel tank and a canister is taught by Japanese Laid-Open Patent Publication No. 2011-256778. In the flow control valve, a valve movable element needs to be moved in a valve-opening direction by a predetermined amount before the flow control valve reaches a valve-opening start position at which a fuel tank and a canister are communicated with each other after the flow control valve initiates a valve-opening operation from an initial condition. Therefore, in order to quickly perform a valve-opening control of the flow control valve, the valve-opening start position is previously learned, so that the valve-opening control is generally started from the learned valve-opening start position. In order to perform such learning, the valve-opening start position has to be determined. A determination of the valve-opening start position is made by detecting a decrease in an inner pressure of the fuel tank.